What is a subchorionic hemorrhage?

What is a Subchorionic Hemorrhage?

A subchorionic hemorrhage (also called subchorionic hematoma) is a collection of blood that forms between the wall of your uterus and the outer membrane surrounding your baby (the chorion), and it's one of the most common causes of bleeding in early pregnancy. 1

How Common Is It?

• This condition occurs in 7% to 27% of pregnancies, so you're not alone if you've been diagnosed with one 1
• It's typically discovered during an ultrasound evaluation when you experience vaginal bleeding in the first trimester 1

What Causes It?

The exact cause isn't always clear, but several factors may contribute:

• Blood clotting issues: Low levels of certain clotting proteins (protein S, antithrombin-III) or elevated homocysteine levels 2
• Immune system factors: Presence of certain autoantibodies (like lupus anticoagulant, anticardiolipin antibody, or antinuclear antibodies) 2
• Blood thinning medications: If you're taking anticoagulation therapy 3
• Problems with placenta formation: Issues with how the placenta implants and develops 2

What Are the Symptoms?

• Vaginal bleeding is the most common symptom—this can range from light spotting to heavier bleeding 4, 5
• Uterine contractions or cramping may occur 4
• Pain can sometimes be present 5
• Some women have no symptoms at all and the hematoma is discovered incidentally on ultrasound 1

How Is It Diagnosed?

• Transvaginal ultrasound is the primary way doctors diagnose this condition 1
• Your doctor will document where the bleeding is located relative to your placenta and check for your baby's heartbeat 1
• Blood tests may be ordered, including a complete blood count to check for anemia and beta-hCG levels to track your pregnancy hormone 1
• If you're Rh-negative, you'll receive a RhoGAM shot (anti-D immunoglobulin) to prevent complications 1

What Does This Mean for My Pregnancy?

The prognosis depends heavily on the size of the hematoma and whether your baby's heartbeat is present:

• Good news: If your baby has a heartbeat, the prognosis is generally better 1

• Small hematomas: Usually have minimal impact on pregnancy outcomes 6

• Medium to large hematomas: Are associated with higher risks, including:

  • Miscarriage (14.4% compared to 6.4% without hematoma) 2
  • Premature rupture of membranes (13.5% vs 3.8%) 2
  • Preterm delivery 3, 6
  • Intrauterine growth restriction 3, 6
  • Placental abruption 6

• Severe cases with persistent symptoms: If bleeding and contractions continue throughout pregnancy, there's a 77% chance of premature labor and 13.6% risk of miscarriage 4

What Happens Next?

• No proven treatment exists for subchorionic hemorrhage—your body needs to reabsorb the blood on its own 3
• Your doctor will likely recommend follow-up ultrasounds to monitor the size of the hematoma 5
• If the hematoma is large or you required a blood transfusion, you may need serial growth ultrasounds, umbilical artery Doppler studies, and fetal monitoring 3
• Bed rest and activity restriction are commonly recommended, though not proven to change outcomes 3
• If you have autoantibodies, your miscarriage risk increases significantly (28.2% vs 7.6%), so closer monitoring is warranted 2

Important Things to Watch For

• Increasing or heavy vaginal bleeding 5
• Severe abdominal pain or cramping 5
• Changes in the amount or pattern of bleeding 5
• Any decrease in fetal movement (in later pregnancy) 3

The Bottom Line

While a subchorionic hemorrhage can be frightening, many women with small hematomas go on to have healthy pregnancies. The size of the hematoma matters most—larger ones carry more risk than smaller ones 5, 6. Your healthcare provider will monitor you closely with ultrasounds to track whether the hematoma is growing, shrinking, or staying the same size, which helps predict your pregnancy outcome 5.